1. Field of the Invention
The present invention pertains to artificial turf, and more particularly to a knitted artificial turf system.
2. Description of the Related Art
Various artificial turf systems have been developed that provide a synthetic turf playing surface for various sports and recreational activities. One example of an artificial turf involves a system wherein fibers are tufted into a primary backing. Various combinations of yarns/fibers are used in the tufted embodiments.
One playing surface is known that includes a subsurface, a pile fabric resembling grass and a compacted top-dressing comprising a mixture of from 25 to 95 volume percent resilient particles and from 5 to 75 volume percent fine sand. The playing surface includes a multi-filament yarn tufted into a woven fabric backing to form a pile fabric with pile elements that resemble grass. A suitable subsurface may consist of concrete or asphalt pavement, compacted clay, or gravel rolled into ordinary dirt.
At least due to tufting, prior art turf systems, among other things, tend to be of a loose construction and may be undesirable for certain applications. Many other problems and disadvantages of the prior art will become apparent to one skilled in the art after comparing such prior art with the present invention as described herein.
An artificial turf is provided that is not tufted. The artificial turf has two face yams, one of which is non-textured, and one of which is textured. The artificial turf is preferably knitted, and the non-textured face yarn or pile has a pile height exceeding about 0.6 inch, preferably having a height of at least about 1.0 inch. In use, the textured pile has a height significantly lower than the pile height of the non-textured pile, preferably a pile height of at least 25% less than the pile height of the non-textured pile. The textured and non-textured pile yarns are knotted together with a stitch-in yarn to form rows of knots in the machine direction of the artificial turf thus made, and lay-in yarns are interlocked with the rows of knots to form a base for the pile yarns. A seal is preferably applied to the backing for additional dimensional stability.
Turf that is constructed according to principles of the present invention has been known to use a knitting machine that may contain over 1,000 needles to produce a width of artificial turf of about 15 feet. The assembly process is more complex than tufting. The pile yarn and stitch-in yarn are inserted into a knitting needle. Lay-in yarn is interlocked with the pile and stitch-in yarn through a separate feed mechanism for the machine. Loops of pile fabric are formed and cut by a slitter. The knitted turf is subjected to a finishing operation in which a suitable seal material is applied to penetrate the contact points in the backing and to stabilize the structure. This process is usually accompanied by a heat treatment that stabilizes the fabric and conditions the pile.
Turf according to principles of the present invention is made using a knitting process. The artificial turf thus formed is preferably mounted on a subsurface, and preferably the subsurface includes concrete or asphalt pavement, compacted clay, gravel, gravel mixed with soil, and then more soil or a foamed product is laid on the subsurface. A fill material such as sand and/or rubber particles is preferably filled in and around the textured and non-textured pile to about the height of the textured pile.
Various aspects of the present invention may be realized through an artificial turf that includes a first face yarn, a second face yarn, a lay-in yarn, and a stitch-in yarn. The second face yarn is textured, for at least the reason of creating a textured zone. A knot is formed by knitting the first face yarn, the second face yarn, the lay-in yarn, and the stitch-in yarn together. A row of knots is also formed in this manner. A backing is formed when the lay-in yarn is extended between at least two rows of the knots and knitted to hold the at least two rows of knots together. A fill material is also placed on top of the backing.
Numerous variations exist with respect to the type of material that is used to create the first face yarn, the second face yarn, the stitch-in yarn, and the lay-in yarn. Of particular interest are the different types of physical shapes and feel that may be given to the first face yarn depending upon factors such as the spinneret that is used to produce the first face yarn and the pellet that is produced for the extrusion with the spinneret.
Various aspects of the present invention may also be found in a method for creating an artificial turf. The method includes, not necessarily in this order, the following steps: extruding a pellet through a spinneret to form an extended ribbon; knitting the extended ribbon into a blend of other ribbon, that has been textured, and stitch-in yarn to form knots; cutting the extended ribbon to create a flat face yarn that has a length of approximately one inch; forming rows of knots from the extended ribbon, the other ribbon, and the stitch-in yarn; and knitting a lay-in yarn into the rows of knots to combine the rows of knots and create a backing for the artificial turf while the combination also creates a textured zone on top of the backing and the flat face yarn extends upwardly from the textured zone.
Other aspects of the present invention will become apparent with further reference to the drawings and specification which follow.